Steam generator and method of preventing turbine accumulations



.N v. 21, 1933- J. K. RUMMEL 1,935,670

STEAM GENERATOR AND METHOD OF PREVENTING TURBINE ACCUMULATIONS FiledMarch 15 1950 INVE NTOR w n 1 W ATTOR N EYS Patented Nov. 21, 1933 STEAMGENERATOR AND METHOD OF PREVENTING TURBINE ACCUMULATIONS John K. Rummel,Westfield, N. J., assignor to The Babcock & Wilcox Company, Bayonne, N.3., a corporation of New Jersey Application March 15, 1930. Serial No.436,246 11 claims. (01. 210-16) This invention relates to a boiler intowhich carbon dioxide is introduced to prevent the accumulation ofcaustic soda. or other sodium compounds. It has been found in practicethat such accumulations of caustic soda or other sodium compounds resultin some of these compounds being carried with the steam into the steamturbine that is being operated by steam from the boiler with aconsequent loss in efficiency and danger to the plates and nozzles ofthe' steam turbine. By this invention these difliculties are overcome. 1

The invention will be understood from the description in connection withthe accompanying drawing which illustrates somewhat diagrammatically howthe invention can be carried out.

In the drawing, reference character 1 indicates the furnace of a boilerthat may be fired, for example, by means of the fuel burners 1'. A

boiler is located in position to be heated by hot products of combustionfrom the furnace 1. This boiler comprises rows of tubes 2'extendingacross the furnace with their ends connected to superposed headers 3 onopposite sides in such a manner that water enters the row of tubes fromthe horizontally disposed inlet header 4 and passes back and forththrough the tubes that are connected in series with each other, thetubes in each row being connected in parallel with each other.

The outlet ends of the upper row of tubes 2 are connected to the outletheader 5 from which a pipe 5' leads to the receptacle 6, which operatesas a steam and water separator. A feed water inlet pipe 7 is connectedto the receptacle 6 from a feed pump or the like (not shown).

A valved pipe 8 extends from the upper or steam space of the receptacle6 to the turbine 9. The exhaust steam from the turbine 9 is dischargedinto the condenser 10 from which a pipe 11 leads to a centrifugal pump12. A pipe 13 leads from the outlet of the centrifugal pump 12 to thefeed pump 14 from which a pipe 15 leads to the header 4.

A valved pipe 16 leads from the lower or water 46 space of thereceptacle 6 to the pipe 13. I

A carbon dioxide tank 1'? that is provided with a pressure gauge 18 isplaced-upon a weighing scale 19. A valved pipe 20 leads away from theupper portion of the tank 17 and-is connected by the flexible connection21 to the pipe 13, so that'a regulated amount of carbon dioxide may beintroduced into the water that enters the pump 14 and may be measured asitfenters.

By introducing carbon dioxide into the water,

' the formation of caustic soda is prevented, due

to the fact that the carbonv dioxide causes the formation of sodiumcarbonate or sodium bicarbonate to take place.

Tests have shown thatwhen water entering the boiler tubes contains ashigh as about 50 0 parts per million of sodium carbonate equivalentwith, say, about 20% or more of it in the form of sodium bicarbonate, noappreciable hydrolysis of the sodium carbonate will take place in theboiler. The sodium carbonate will remain as dust in the superheatedsteam that leaves the boiler and will not produce any more harmfuleffects upon the turbine efliciency or blades than other solid materialproduces. This dust does not have a strong tendency to form depositswithin the turbine as is the case with caustic soda, which, because ofits physical and other properties, solidifiesand often acts as a binderfor the precipitation of other solids upon the turbine blades andnozzles. A calculation will 75 show that with 50 parts per million ofsodium carbonate equivalent present in the boiler feed water, theaddition of 4.15 lbs. of carbon dioxide per million lbs. of feed wateris sufficient to convert about 20% of the sodium carbonate equivso alentinto sodium bicarbonate. It has been found that the amount of carbondioxide required to convert the sodium compounds into the form that willnot form or assist in the adherence of deposits upon the turbine bladesor nozzles is 5 suflicient when enough carbon dioxide has been added tocause about 20% ofthesodium carbonate equivalent to lee-converted intosodium H bicarbonate.

In certain cases, it other compounds with the CO1. For example, if thealkali concentration becomes too high, phosphoric or sulphuric acid ortheir-acid salts may be added to neutralize a part of the excessalkalinity and thus reduce the amount of CO:

may be advisable to add 90 4. The process of treating boiler water whichcomprises introducing feed water containing sodium compounds into aboiler and adding a sufli cient amount of carbon dioxide to cause asmuch as about or more of the sodium carbonate equivalent to be convertedinto sodium bicarbonate.

5. The process or treating boiler water which comprises introducing feedwater containing about 50 parts per million of sodium carbonate into aboiler and adding approximately four pounds of carbon dioxide permillion pounds of water. L

6. The process of treating boiler water which comprises introducing feedwater containing sodium compounds into a boiler and adding suflicientmineral acid to neutralize a part of the sodium alkalinity therein,while adding carbon dioxide in suillcient amount to form sodiumbicarbonate in said Iced water.

'7. In a steam turbine-boiler power plant, the method of minimizingdeposits in the turbine of adhesive sodium compounds carried over insteam generated in the boiler from water containing a sodium compound,consisting of adding carbon dioxide to the boiler water.

8. In a steam turbine-boiler power plant, the method of deposits in theturbine of solids carried over in steam generated in the boiler fromwater containing a sodium compound which tends to be converted thereininto a second sodium compound having a high adhesive property,consisting of adding carbon dioxide to the boiler water in sufllcientquantity to minimize the amount of said first compound so converted. 9.In a steam turbine-boiler power plant, the

method of minimizing deposits in the turbine of solids carried over insteam generated in the boiler from water containing a sodium compoundwhich tends to hydrolyze at high temperature into a second sodiumcompound having a high adhesive property when separated, consisting ofadding carbon dioxide to the boiler water in sufficient quantity tominimize the hydrolysis reaction.

10. The method of treating steam boiler water containing a sodiumcompound tending to hydrolyze at high temperatures into another sodiumcompound having a high adhesive proprty when separated from the water,consisting of adding carbon dioxide to the boiler water in sufl'icientquantity to convert a substantial portion of said compound intobicarbonate, and thereby minimize the hydrolysis reaction.

11. The method of treating steam boiler water -containin'g a sodiumcompound tending to hydrolyze at high temperatures into another sodiumcompound having a high adhesive property when separated from the water,consisting of adding carbon dioxide to the boiler water in sufiicientquantity to substantially increase the partial pressure of carbondioxide in the water and thereby minimize the hydrolysis reaction.

JOHN K. RUDD/EL.

